Table of Contents

Preface xi Acronyms xv Chapter 1 Quality of Service Mechanisms and Metrics 1 Traffic Management Mechanisms 1 Traffic Conditioning 4 The Metering Function 5 Marker 9 Dropper 9 Shaper 10 Admission Control 11 Nodal Mechanisms 15 Transmission Scheduler 15 Buffer Management 22 Feedback Congestion Management 26 Performance Metrics 31 Throughput 32 Delay 33 Packet Loss 36 Simple Queueing Models 36 MMl Queueing System 38 MG 1 Queueing System 41 Chapter 2 QoS Architectures 43 Reservation Model 43 Reservation Model Example 45 Service Types 49 Differentiation Model 54 Differentiating Model Examples 56 IEEE Standard 802. IQ Ethernet Frame Priority 62 Chapter 3 IEEE Standard 802.11 Overview 65 IEEE 802.11 Architecture and Frame format 65 IEEE 802.11 PHY Overview 69 IEEE 802.1 la PHY 69 IEEE 802.1 lb PHY 71 The IEEE 802.1 lg PHY Overview 73 The IEEE 802.11 MAC Overview 75 Distributed Coordination Function (DCF) 75 Point Coordination Function (PCF) 81 Power Management 85 IEEE 802.11 Throughput 86 IEEE 802.11 Frame Types 90 A Queueing Model for PCF Performance 92 Chapter 4 IEEE 802.11 QoS Features 97 IEEE 802.1 le MAC Overview 97 Data Frame Format 99 Association to QoS BSS 102 EDCA Operation 105 HCCA Operation 108 Admission Control 110 EDCA Admission Control 119 HCCA Admission Control 123 Direct Link Setup 125 Block Acknowledgment (BA) 129 Throughput Improvement Due to Block Acknowledgment 132 Power Management Using APSD 134 WiFi Multimedia (WMM) Specification 136 IEEE 802.1 In (High Throughput) MAC Features 139 Frame Aggregation 139 IEEE 802.1 In Block Acknowledgment 141 A Simple Engineering Example 143 Chapter 5 Interworking with WLAN QoS 145 Common WLAN Deployment Scenario 147 WLAN QoS Interworking with Ethernet 148 WLAN QoS Interworking with IP Networks 151 Chapter 6 Concluding Remarks 157 Bibliography 159 Index 163

About the Author

Osama Aboul-Magd holds a Bachelor of Science degree in Electrical Engineering from Cairo University, as well as an M.A.Sc. and Ph.D. from the University of Toronto. As a Senior Advisor for Nortel Networks, he is involved in the planning and design of QoS and traffic management features for many products covering multiple technologies including Frame Relay, ATM, IP, and Ethernet. In addition to his interest in WLAN QoS and MAC related issues, Mr. Aboul-Magd has made numerous contributions to the standards development community. He was a key leader in the ATM Traffic Management specification at the ATM Forum and editor of the Ethernet Traffic Management Specification at the Metro Ethernet Forum. Mr. Aboul-Magd also co-authored the IETF (MPLS WG) proposed standard, Constraint-Based LSP Setup Using LDP and was a primary author of the OIF optical user-network interface (O-UNI) implementation agreement, OIF2000.125.6, Sept. 2001. In 2003, he began participating in the IEEE 802.11 Working Group, increasing his involvement in the standards development process. Throughout his career, Mr. Aboul-Magd has developed over twelve patents in various technology arenas.